Bearings configured to support main shafts of turbo machines, such as a gas turbine and a turbocharger, are required to endure severe environments involving high temperature and high speed rotation. Attention has been focused on a foil bearing as a bearing suited to use under such conditions. The foil bearing has bearing surfaces formed of flexible thin films (foils) having low flexural rigidity, and is configured to support a load by allowing the bearing surfaces to be deflected. During the rotation of the shaft, fluid films (such as air films) are formed between an outer peripheral surface of the shaft and the bearing surfaces of the foils, and the shaft is supported in a non-contact manner.
For example, in Patent Literatures 1 and 2, there are disclosed so-called multi-arc foil bearings in which a plurality of foils are arrayed in a circumferential direction, and both circumferential ends of each of the foils are mounted to a foil holder (housing). In those foil bearings, both the circumferential ends of each of the foils are brought into abutment against projecting portions projecting radially inward from an inner peripheral surface of the foil holder (shift suppressing portions 62 in Patent Literature 1 and ridges 70 in Patent Literature 2). In this way, both the circumferential ends of each of the foils are held on the foil holder.